The synthesis of myocardial contractile proteins will be studied in pressure and volume loading using the perfused guinea pig heart in vitro with constant infusion of two labeled amino acids, 3H-lysine and 3H-phenylalanine. The relative molar synthesis of actin, tropomyosin, myosin light chains 1 and 2 will be compared to that of myosin heavy chains in these stresses. Experiments completed in this period have already demonstrated that there is a relative increase in synthesis of myosin HC compared to myosin LC's in afterload, and the difference in preload or volume loading will be determined. Synthesis of cardiac total protein as well as contractile proteins will also be assayed in hearts taken from young animals exposed to prolonged ethanol use in order to see if changes which appear will allow clarification of the development of alcoholic cardiomyopathy.